> I wonder how you manage to keep track of everything with this huge all-in-one main.c

To me it's not different from having multiple files, on the contrary it's even easier to do search and replace

> Do you plan to achieve 100%?

Yes!

> Is there a list of what is actually missing and which relevant projects depend on the missing parts?

Yes, a partial list is in "Known bugs and limitations" in NOTES.

> What are the core benefits compared to e.g. ECL or CLISP?

Well, the code base is smaller and (arguably) easier to read. Building is easier. There's a debugger with stepping, very easy to use

Amazing work, thanks.